The Solar Backscatter Ultraviolet instrument
currently onboard the NOAA-16 polar orbiting satellite measures
the ultraviolet sunlight scattered by the Earth's atmosphere
at several wavelengths ranging from 252 nanometers (nm) to
340 nm. Measurements at the shortest eight wavelengths are
used to estimate ozone vertical profiles by using a maximum
likelihood retrieval algorithm. Measurements at the longer
four wavelengths, which penetrate into the lower atmosphere,
are used to obtain estimates of total column ozone. Total
ozone is calculated by using the ratio of two wavelengths
of backscattered

One of NOAA's polar orbiting satellites
carrying the SBUV/2 instrument.

ultraviolet light where one is strongly
absorbed by ozone while the other is absorbed very little. For
example, the ratio betwee 312 nm and 331 nm can be used in this
calculation of total columnar ozone.

Ozone measurements via satellite have been made
by this type of backscatter ultraviolet
instrument since the launch of the Nimbus-4 satellite in April
1970. The improved Solar
Backscatter Ultraviolet Instrument (SBUV) was launched in November
1978 and continued until the second generation instrument, the
SBUV/2, began with the NOAA TIROS series of satellites in 1984.

Operational monitoring of stratospheric ozone
began in 1985 with the NOAA-9 satellite and continued to present
with the NOAA-11, NOAA-14 and NOAA-16 series. The latest in
the series of NOAA polar orbiting satellites, NOAA-M, will also
be equipped with an SBUV/2 ozone-measuring instrument when it
launches in 2002.

For additional information on the SBUV/2, visit
the NOAA-KLM
SBUV/2 website and see sections 3.8 and 7.4. Also
visit NOAA/NESDIS's SBUV/2 web site. Raw retrieval data (not
maps, as are provided at sites available through links under
the data menu on this page) are available through NCDC's satellite
services and by anonymous
ftp in the pub/crad2/ directory.